In 2012 the Toyota Prius Advanced from Being a Single, Global Model to Become a Family
Updated: January 2016
TOYOTA PRIUS+
In 2012 the Toyota Prius advanced from being a single, global model to become a family of full hybrid vehicles. In Europe the first stage of this development was the introduction of Prius+, the first full hybrid seven-seat vehicle to be sold in the region. This was later joined by Prius Plug-in, a new version of the world’s best-selling hybrid that delivers even greater fuel efficiency and low emissions thanks to a rechargeable lithium-ion battery.
These additions to the Toyota range, together with Yaris Hybrid, Auris Hybrid and third-generation Prius, demonstrate the fundamental adaptability of Toyota’s Hybrid Synergy Drive to work in different size vehicles.
Prius, Prius+ and Prius Plug-in have expanded Prius’s customer base and sales potential. Prius+ is designed for growing families who need the space and flexibility of a seven-seater, while Prius Plug-in, with CO2 emissions from as low as 49g/km, appeal to environment-conscious early-adopters.
For 2015, Prius+ received its first major revisions, with improvements to the exterior styling, the introduction of advanced technologies for safer journeys and the addition of Toyota’s latest multimedia and connectivity features. Customer choice was increased as well, with the addition of a third equipment grade, Excel Plus.
DESIGN
· Exterior retains the characteristic Prius triangle silhouette
· New frontal styling for 2015 model year
· Aerodynamic design supports fuel economy, handling stability and quiet performance
· Interior accommodates seven, with ample luggage space
· Split/fold/slide functions for second row seats and split/fold third row
Prius+ was designed from the ground up, but it bears design hallmarks that show it to be an evolution of the original Prius.
As its name suggests, it offers significantly more space on board, while maintaining an overall compact size to ensure excellent aerodynamic performance. Overall it measures 135mm longer than a standard Prius, 30mm wider and 85mm higher. The wheelbase has been extended by 80mm, which makes it possible to seat seven inside, in three rows of seats.
Exterior design
The car’s characteristic triangle silhouette makes it easily recognisable as a member of the Prius family, and it also shares the clean and strong front-end design styling that helps manage the flow of air over the vehicle. The full benefits of the lightweight high tensile steel and aluminium construction and the quiet Hybrid Synergy Drive powertrain are supported by an exterior designed for maximum aerodynamic efficiency. This helps improve fuel economy, handling stability and quiet performance.
Prius+ was given a more impactful appearance for 2015 with a new frontal treatment that adopts the latest Toyota styling cues.
The revised front-end features a new upper grille and a more prominent Toyota badge that extends the forward line of the bonnet. There are new LED headlights, too, which use a cylindrical projector for both high and low beam. Their slim profile and contrasting black and chrome plating give Prius+ a distinctive sharp-eyed appearance.
The lower grille adopts the trapezoid shape that’s a common feature of the latest Toyota models. With a gloss black metallic finish, it adds emphasis to the car’s broad stance. The impression of width is reinforced by a re-working of the bumper corners, given extra emphasis in a flowing form that extends from the headlights to the new air intakes and LED daytime running lights.
At the rear the top-hinged tailgate is flanked by a new combination lamp design with “light guide” treatment and red inner lenses that give the car an individual lighting signature. Following the styling themes adopted at the front, there is a new licence plate trim and bumper with an integrated diffuser.
In profile Prius+ retains the familiar Prius triangle silhouette, but develops the design with spindle shape created by the long, seamless flow of the bonnet, A-pillar and roofline, the clean sweep of the full-length side glazing, emphasised by blacked out centre and rear pillars, and a rising crease line in the lower bodywork which flows unbroken into the rear bumper.
The smooth convergence of airflow from the roof and sides of the vehicle is vital to Prius+ aerodynamic efficiency. The body itself tapers in shape, and the flow of air away from the vehicle is smoothed by a roof spoiler that has been optimised for length and angle, an air-kick shape worked into the rear light units, and aero corners on the rear bumper.
Spats fitted at the front of each wheel arch suppress airflow changes around the tyres, improving the car’s straight line stability and steering.
Working together, these elements give Prius+ a drag coefficient of Cd 0.28.
The Hybrid Synergy Drive system is represented in a series of external features, including badging and blue detailing on the headlamps. Seven exterior colours are available: Pure
White, Decuma Grey, Galaxy Black, Tyrol Silver, Orion Blue, Sienna Bronze and White Pearl.
Sixteen-inch alloy wheels with aerodynamic wheelcaps are featured on the Icon model and 17-inch alloys are standard on the Excel and Excel Plus; all are fitted with tyres with a rolling resistance five per cent lower than those used by the standard Prius.
Interior design
The interior design features a horizontal dashboard that encompasses the centre console and instrumentation in a single flowing form. Combined with a concave door trim and a well-defined space between the centre console and instrument cluster that links the driver and front passenger, it creates a great sense of spaciousness.
The console flows into an instrument binnacle that is mounted centrally on top of the dashboard. The hybrid system indicator and speedometer are positioned within the binnacle, close to the steering wheel, so minimising driver eye movement from the road ahead.
Changes in the cabin for 2015 include a dark silver metallic finish for the driver’s switchgear and the air conditioning dial control and a chrome finish for the door handles.
There two new chrome-trimmed, slim-line air vents in the centre console and a new 4.2-inch colour TFT information screen, controlled using switchgear on the steering wheel. As well as basic information such as clock, trip indicator, cruising range fuel consumption, the screen also displays the Hybrid System Indicator and Energy monitor – features common to all Toyota hybrids. It also provides a new “Eco Judge” function, designed to help the driver maximise the powertrain’s efficiency, giving a points score for their eco-driving style.
The screen will also mirror the settings for the air conditioning and audio settings, keeping them in the driver’s line of sight when on the move.
The instruments and switchgear in the central section are clearly divided between those for driving and those for other functions. All the driving-related switchgear is positioned close to the steering wheel and set within a trim with a metal-like finish.
The cabin uses contrasting finishes and soft-touch materials to give an advanced look and feel. Hayama grey cloth is used on the Icon and Nagara black leather upholstery on the Excel and Excel Plus.
Three-tier, seven-seat packaging
Prius+ wheelbase is 80mm longer than that of the standard Prius, at 2,780mm. The rear overhang is also longer by 50mm. The extra length means there is significantly more space for passengers and luggage.
The seven-seat format features three independent sliding/split-folding second row seats and a 50:50 split-folding third row. It’s been possible to fit a third tier of seats by locating the hybrid system’s spacing-saving lithium-ion battery pack in the centre console, between the front seats.
The couple distance is key to passenger comfort and in Prius+ the measurement between the front and second row seats is 965mm, 35mm more than in Prius, while that between the first and third row is a class-leading 1,635mm. Knee room in the second and third rows has been improved by an extra 25mm by using a thin, curved seatback design for the front and second row seats.
Everyone on board has a good view out, thanks to each row of seats being set 45mm higher than the one in front. This has been achieved while maintaining good headroom throughout the vehicle.
The front seats have 25mm more headroom, 27mm more shoulder room and 18mm more hip room than in Prius. They have 260mm slide and 60mm height adjustment, can be fully reclined, and come with electric lumbar support adjustment as standard. A new seat frame design means they give a better fit and lateral hold, too.
There are gains for second row passengers as well, with 75mm more headroom and 59mm more shoulder room compared to Prius. The three seats can be individually slid, reclined and folded. The outer seats have a sliding range of 180mm and the one in the middle can be moved through 165mm. This enables a staggered seating plan that can provide more shoulder room for adults. All three seats can be folded fully flat to maximise the loadspace. Each can be reclined by up to 35 degrees.
With all seats in place, Prius+ has 232 litres of cargo space up to the roof. With the third row stowed, this figure rises to 784 litres, and when all the rear seats are folded flat, a maximum 1,750 litres is available. Loading is made easier thanks to the 1,105 by 730mm tailgate – 95mm wider and 85mm higher than that on Prius.
The storage is flexible, too, with a 345mm-deep 60-litre storage tray beneath the luggage deck. There is room enough to take shopping bags, or a suitcase or baby buggy which can be stored vertically by flipping up the deck board.
There are also plenty of storage spaces around the cabin. Up front there is an 8.5-litre glovebox, 4.5-litre upper glovebox and an accessory space on the side of the driver’s seat. The side-opening two-litre centre console box can hold up to eight CDs and can be accessed from both the front and second row seats. The unit includes a dedicated tray for storing a USB-connected phone or digital music player.
The front and rear door pockets are large enough to take A4 documents or plastic bottles, and there are five cupholders divided between the three rows of seats.
POWERTRAIN
· First non-plug-in Toyota full hybrid to use a lithium-ion battery
· Compact, high-output lithium-ion battery located in the centre console
· Improved exhaust heat recirculation system and change of electric motor cooling from air to liquid
· Reduced final drive gear ratio enables acceleration to be matched with standard Prius
The principal elements in Prius+ Hybrid Synergy Drive system are a 1.8-litre VVT-i petrol engine, a powerful electric motor, a generator, a high-output lithium-ion battery, a power control unit and a power split device.
The engine and motor will work together or independently to maximise efficiency according to driving conditions and driver demands, giving the best balance of performance and fuel economy.
During deceleration and under braking, the electric motor works as a high-output generator to effect regenerative braking, recovering kinetic energy that would normally be lost as heat and storing it as electric power in the high-output battery.
The system drives through a seamless, electronic continuously variable transmission (E-CVT), controlled using shift-by-wire technology and an electronic shift lever.
As in the standard Prius, Prius+ offers three on-demand drive modes to tailor performance of the hybrid powertrain to suit driver preferences. These include an all-electric EV mode for near-silent running with zero tailpipe emissions.
Lithium-ion battery
Toyota has adopted lithium-ion technology for the first time in a non-plug-in hybrid, reaping the benefits of significant weight saving and more compact packaging. As the battery is much smaller than the nickel-metal hydride type used in the standard Prius, it has been possible to fit it inside the centre console, between the front seats.
Its new design houses 56 cells, arranged vertically in a double-stacked structure. As well as being smaller in volume, it weighs just 34kg – 8kg less than the battery in Prius.
1.8-litre Atkinson cycle engine
The light and compact, four-cylinder, 1,798cc Atkinson cycle petrol engine develops a maximum 97bhp/73kW at 5,200rpm and 142Nm of torque at 4,000rpm. Adopting the Atkinson cycle, and introducing a cooled exhaust gas recirculation system, provides valuable gains in fuel efficiency and reduces emissions.
In contrast to a conventional Otto cycle engine, the intake valves on an Atkinson cycle engine close late, delaying compression. This creates a high expansion ratio for less compression, reducing intake and exhaust energy losses and converting combustion energy into engine power more effectively. As a result, the exhaust temperature is lower than in conventional engines. Cooled exhaust gas is reintroduced into the intake system, which further reduces the engine’s operating temperatures.
Together these technologies minimise situations when the cooling effect of fuel enrichment is needed to protect the catalytic converter from overheating damage, thus improving fuel economy and cutting emissions.
Prius+ engine heat management system combines the improved exhaust heat recirculation system with an electric water pump to help improve fuel consumption and cabin comfort in cold weather. To reduce mechanical losses, an electric system is used in place of a conventional water pump and drive belt, which allows the coolant flow rate to be controlled more precisely.
The exhaust heat recirculation system directs exhaust gases via a valve in the exhaust assembly to heat the engine coolant at start-up. The system is 33 per lighter and 27 per cent more efficient than that used in the standard Prius engine, and it enables a greater amount of heat to pass from the exhaust to the coolant in the heat exchange system. This allows for more rapid delivery of effective cabin heating, while also improving the efficiency of the hybrid system and overall fuel economy.